Variation of Yield Related Traits, Flower Morphology and Pollen Viability in some Iranian Thymus Species

In this study, 16 ecotypes of different species of Thymus were evaluated for morphological and flower related traits (plant height, canopy diameter, leaf length and width, plant dry weight, 1000 grain weight, number of day to flowering, flower length, flag and pistil length, number of flag and pollen viability) in a Randomized Complete Block Design with three replications at the Research Center of Agriculture and Natural Resources in Isfahan. Analysis of variance showed significant difference between studied species for these traits. Mean comparison showed that the highest amount of dry weight was  belonged to  Thymus kotschyanus species from west Azerbaijan. Therefore, this genotype can be offered, if the purpose of breeding program is increasing of plant dry weight. Study of correlation between traits showed that dry weight had a significant negative relationship with 1000 grain weight and pollen viability percentage. Stepwise regression analysis showed that flower length, number of flags, large canopy diameter, percentage of pollen viability, flag length and 1000 grain weight justified variation of plant dry weight, and therefore these traits are the most important component of plant yield. Cluster analysis on the studied species could divide them into 4 distinct groups. The results showed that these groups did not follow geographical distribution.